twisted.flow.stage.Callback

Package twisted :: Package flow :: Module stage :: Class Callback

Class Callback

Instruction --+    
              |    
          Stage --+
                  |
                 Callback

Known Subclasses:: _Protocol

Converts a single-thread push interface into a pull interface.

Once this stage is constructed, its result, errback, and 
finish member variables may be called by a producer.   The
results of which can be obtained by yielding the Callback and
then calling next().   For example:

    source = flow.Callback()
    reactor.callLater(0, lambda: source.result("one"))
    reactor.callLater(.5, lambda: source.result("two"))
    reactor.callLater(1, lambda: source.finish())
    printFlow(source)

Method Summary
	`__init__(self, *trap)`
	`__call__(self, result)` called by the producer to indicate a successful result
	`_yield(self)` executed during a yield statement by previous stage
	`errback(self, fail)` called by the producer in case of Failure
	`finish(self)` called by producer to indicate successful stream completion
	`result(self, result)` called by the producer to indicate a successful result
Inherited from Stage
	`__iter__(self)`
	`next(self)` return current result

Class Variable Summary
`class`	`Instruction` = `twisted.flow.stage.Instruction`

Method Details

call(self, result)
(Call operator)

called by the producer to indicate a successful result

_yield(self)

executed during a yield statement by previous stage

This method is private within the scope of the flow module, it is used by one stage in the flow to ask a subsequent stage to produce its value. The result of the yield is then stored in self.result and is an instance of Failure if a problem occurred.

Overrides:: twisted.flow.base.Stage._yield (inherited documentation)

errback(self, fail)

called by the producer in case of Failure

finish(self)

called by producer to indicate successful stream completion

result(self, result)